Dissipation-induced rotation of suspended ferromagnetic nanoparticles

TL;DR

This paper demonstrates that isotropic ferromagnetic nanoparticles in a viscous liquid can be made to rotate using a rotating magnetic field, driven solely by magnetic dissipation, with a theoretical model supporting the phenomenon.

Contribution

The paper introduces a theoretical framework explaining dissipation-induced rotation of isotropic ferromagnetic nanoparticles, distinct from anisotropic cases, supported by analytical solutions.

Findings

Analytical steady-state solutions for magnetization and rotation.

Dependence of angular velocity on model parameters.

Discussion on experimental observability.

Abstract

We report the precessional rotation of magnetically isotropic ferromagnetic nanoparticles in a viscous liquid that are subjected to a rotating magnetic field. In contrast to magnetically anisotropic nanoparticles, the rotation of which occurs due to coupling between the magnetic and lattice subsystems through magnetocrystalline anisotropy, the rotation of isotropic nanoparticles is induced only by magnetic dissipation processes. We propose a theory of this phenomenon based on a set of equations describing the deterministic magnetic and rotational dynamics of such particles. Neglecting inertial effects, we solve these equations analytically, find the magnetization and particle precessions in the steady state, determine the components of the particle angular velocity and analyze their dependence on the model parameters. The possibility of experimental observation of this phenomenon is also discussed.